Fluid control valves



Oct. 22, 1957 G. sELwooD l-:rAL

FLUID CONTROL VALVES Filed Jan. 2s, 1956 Auk INVENTOES GEORGE SELwoob FxEbEmcK J. Ful-1u.

EbwAEb T. EuTLEbGe Wauw ATTQRNEYS United States FLUID CONTROL VALVES George Selwood, Frederick James Fuell, and Edward Tom Rutledge, Hayes, England, assignors to The Fairey Aviation Company Limited, Hayes, England, a British company Application January 23, 1956, Serial No. 560,828

Claims priority, application Great Britain January 24, 1955 6 Claims. (Cl. 137-1620) This invention relates to fluid control valves and one application for which the invention is particularly though not exclusively suitable is to a hydraulic changeover valve for use in a hydraulic servo system employing a high presure for example of the order of 4,000 lbs. per square inc In such applications various forms of slide valve have previously been proposed, in some of which the moving member in constructed and arranged so that the iluid pressure acting on it has a resultant tending to force the ported surfaces together. Preferably this resultant corresponds to the Huid pressure on only a small fraction of the total area of the slide. One diiculty with such a construction, when employing very high pressures, is that in one position of the valve the high pressure canrbe applied to one working port or a portion of it and the low pressure to another working port or portion of it, whilst in another position of the valve the reverse condition will occur. The pressures on these surfaces are liable to produce a tilting eftect which increases the frictional resistance to movement of the valve. In a servo system where the ,valve should respond to .a minimum force this is yclearly undesirable and in extreme cases jamming of the valve may even tend to occur.

An object of'the invention is to provide an improved construction which avoids these disadvantages.

According to one aspect of the present invention, a fluid control valve includes a movable member mounted to vro-` tate about an axis relatively to a platen member, the movable member and the platen affording co-operating end surfaces having in them ports, high pressure and low pressure ports in one member and inlet and outlet ports in the other, in which there are more than one high pressure port interconnected so that the fluidpressures in them are the same and positioned and dimensioned so that the resultant force between the members does not tend to tilt the movable member. For example there may be a pair of high pressure ports centred on a straightline through the axis and on opposite sides of it.

According to another aspect of the present invention, a iluid control valve includes a movable member mounted to rotate about an axis relatively to a platen member, the movable member and the platen affording co-operating end surfaces having in them co-operating ports in pairs, whereof each pair comprises two ports in one of the members centred on a straight line through the axis and on opposite sides of it, the two ports of each pair being interconnected so that the uid pressures in the twoports of any one pair are the same. Conveniently the co-operating surfaces of the movable member and the platen are at, thereby facilitating accurate grinding. The product of the area and the distance of centre of area of the axis for one port in any one pair may be equal to the same product for the other port of the same pair to achieve the desired balancing eiiect of the fluid pressures.

One member may include a pair of high pressure and a pair of low pressure ports, while the other includes a pairofinlet and ,a pair of outlet ports arranged so that in s l ce 2,810,399

, Patented oct. 22, 1957 a central position of the movable member no port in any one member communicates with a port in the otherand the ports are arranged around the axis in the order, high pressure port, inlet port, low pressure port, outletport, and so on. In considering 'the order of the ports arranged about the axis, two adjacent interconnected ports count as one port. Preferably movement of the movable member from the central'position puts the high pressure ports into communication with the inlet or outlet ports as the case may be, before the low pressure ports come into communication with the outlet or the inlet ports.

Preferably the moving member is constructed and arl ample, the ported movable-member may be one of a pairof telescopically connected sleeves both arranged to turn together about the axis of rotation and interposed between the ported` platen and an opposed surface of a second platen, the arrangement being such that the fluid pressure acting on them has a resultant tending to fonce them apart, thereby forcing the ported surface of one sleeve against the ported platen and forcing the opposite surface of the other sleeve against the second platen. Preferably the resultant force corresponds to the fluid pressure on only a small fraction of the total overlapping area between the sleeves. Y l

In one form of the invention the two platens are mounted in an outer body and are held spaced apart by a spacer engaging their opposed surfaces so as to hold them accurately parallel, one or each platen being free to shift Slightly so as to enable both platens to engage the t spacer. The spacer may for example be a sleeve surrounding both the moving members. Conveniently the second platen is constructed and arranged so that the iiuid pressure acting on it has-a resultant tending to force it towards the ported platen so as to maintain both platens firmly in valve for a high-pressure servo system employing a pressure yof some 4,000 lbs. per square inch, with reference to the accompanying drawings of which Figure 1 is a sectional elevation of the valve on the line I-I in Figure 2, f Y

Figure 2 is a section on the line lI-II in Figure 1 and Figure 3 is a section on the line III-III in Figure 1.

The valve is mounted in a housing 1 formed by a generally tubular valve body having lugs 2 projecting at the corners of a square to receive bolts 3 by which it is bolted to a base block 4. Projecting through a hole in the closed end of the body remote from the base block 4, which will be referred to as the top end, is a spindle 5 for operating the valve, having, outside the housing, an operating arm 6for connection -to the controlling mechanism (not shown). Resting on the base block 4 in the lower part of the tubular bore in the body 1 is a ported platen 7 -in the form of a thick disc having in it a number of ports referred to below. A second or upper platen 8 is also contained within the bore of the valve body and is spaced from the ported platen 7 by means of a spacing sleeve 9 engaging the peripheral portions of the two platens 7 and 8 and fitting fairly closely in the bore of the body 1. The ends of. the spacing sleeve 9 are accurately ground so as to maintain the opposed faces of the two platens 7 and 8 accurately parallel.

In the chamber formed between the opposed faces of the two platens and their spacing sleeve is mounted the moving member of thevalve, which comprises a pair of sleeves 11 and 12 telescopically arranged one within the other. The Iupper, outer sleeve 11 has an inwardlydirected flange 13 at its upper edge and its upper surface ing ring 1S, whilst at its lowerend ithasa slight-QtJtW-.fdlyprojecting V.flange 16. `Its lowersunface in .its 4pints,

described below, Vand engages Ytheported `surface lof fthe lower platen 7.

The spindle 5 is formed with ,dogs lfto.engagerecesses formed in the .bore of `the .inner valve `sleeve ,12 so as to transmit ya yrotary Vmovement .from thespindleY .5 :to lthe sleeve 12 whilst ,permitting slight relative movement Iin other directions. The spacing sleeve 9 -has near its lower end an .internal ycircumferential rib 1,8 accurately vground to centre the inner vvalve sleeve 12. The lower end ,-1-9 of .the spindle `5 is .carried in .a bearing in the. lowerplaten 7 and has-a circumferential groove-receiving :a sealing ring 2.1, whilst the -upper vend 22 :of the .spindle 5 is carried in 1a bearing inthe upperfendof the valve body and Ialso has Vin it a circumferential groove -to receive a sealing ring 23. 1

The upper end `:of ,the bore in the val-ve body .1 is of reduced .diameter as .comparedrwith .the lower part,and the upper platen vhas a spigotportion `24 extending :asia piston into this reducedportion of v`the boreand provided with a sealing ring 25 .in a .circumferential groove. A bore extends Lthroughthis upper platen:8 .toallowthe passage/ofthe `spindle Sand also to provide an annular 4.clearance passage'26-aroundfthe spindle. Y,

The spacing sleeve 9 between the platens 7 and 8 'has in its wall a lnumber of openings 27 and-its centralfportion is surrounded by an annular recess `28 vformed in the kwall ofthe `bore of the valve body 1, which ycommunicates through a suitable coupling 29 with Vthe high pressure side of a liquid supply. The upper reduced Yportion 4of `the v,bore inthe valve body has a similar coupling `t1 communieating with the low pressure return-pipe of the `'liquid -supply. `Accordingly the space surroundingthe valve sleeves 11 and 12 is in communicationwith the-high pressure side of the-supply, and in -addition'the iperipheralzedge :ofzthe upper platen 8 is formed with a number .of inotches $2 so as :to admit 'thisjpressure to `the upper :surface `of'the enlarged part .of the upper platen. the `return line is communicated to the interiorof the valvesle'eves 11 and 1-2 throughzthe :opening 'in theiupper platen and is also applied to the upper vendrof ,the spigot portion 24 of the upperplaten.

Accordingly the high pressure acts on ,the lower `end face of the outer valve sleeve 11 whilst the'upperfacefis sealed against the platen 18 and `accordinglyga:resultant upwardtorce is exerted on -theouter -valve sleeve. iSimilarlyv the high pressureacts on the upper surface jofztlie external ilange A16 at the bottom ofzthe inner valve ysleeve 12,' whilstiits under surfacezis sealed against the lower 7 platen :so .that .a resultant .downward force gislexeraed :on the inner valve sleeve. lAlthough these tareas .are lnot large ithe force :may fnonetheless be excessive and iin rthis event :the extreme :outer portions :.ofthe surfacesnf the valvesleeves Aengaging :the platens .may :bekrelieved as zat 33 -so las `toadmit :the :high .pressure to them fandrthereby re'duce the resultantlforceiurging themlapart. :A circular 'leaf or other formfof spring34gmay be interposed-between 9 and ...also .urging thespacingsleeve-downwardsonto.the 1 lower.,platen 7 :so as :to :retain-'the two gplatensewith f their opposed :faces held faccuratelymarallel byV4 the spacngssleeve. Y v Y Y i Ihedowenplaten .7:has3formcd5imittwopairsrof work'- The low pressure `ot' f A Eem-,899. A A A ing ports 36 and 37. Each pair comprises two equal ports at equal distances hom the axis of the spindle 5 'at diametrically opposite positions. Each pair of ports communicates with longitudinal passages 3S, 39 in the base block 4, to which they may vhe connected by liners 41 and sealing rings 42, and the two ports of each pair are interconnected by a .diametrical connecting passage 43 or .44 formed in the base block. The two diametrical connecting passages are formed at different levels so as to cross one another `without meeting. Each diametrical connecting passage is also connected by a radial passage 45 or 46 with a longitudinal inlet or outlet pipe connec- Ytion 47 or 47', the outer ends of the radial and diametrical passages being plugged. The longitudinal inlet and -outlet pipe connections 47, 47"may conveniently serve -wall lof the inner valve sleeve 12 and -hence communicates with the high pressure side of the supply. -In the central position of the valve each high pressure port 49 is situated between two of the workingports 36 and37 of the lower l platen 7, one working port of each pair, but slight movement of the valve in one direction or the other about `its axis will =bring the high-pressure ports 49 partially into register with the two working ports of one pair 36., or the two Working ports of lthe other pair 37, according to the direction of rotation.

v'Thus each high pressure port may be said to lie normally between two working ports. Correspondingly situated outside the working ports are the two pairs of low pressure ports 51. The two ports of each such pair are again identical and diametrically placed with respect to the axis.V l

All these four ports 51 open into the interior ofthe inner valve sleevej12 and thereby communicate with the low pressure side of the system.

From what has'been said it will be appreciated thatin the central position of the valve the low pressure ports v51 Y are just clear of the working ports 36 and 37 but slight turning of the valve in one .direction will bring 4 one ypair of Vlow pressure ports into communication with one pair of workingports whilst slight movement in the other direction will bring the other pair of low pressure ports .into

Y 4partialregister Withpthe other pair of working ports. -ln

ment is obtained.

Figure 3 the valve is shown with `the high pressure .ports 49 just overlapping the working ports 36.

'The valve laps arepreferably arranged so vthat .the Aliigh pressure ports 49 communicate with the vworking ports 36 `or 37 slightly before the low pressure ports 51 do-so. Ac-

cordinglythe high pressure will iirst be communicated to the jack-or ram of the servo system, but .no .movement can occur until the low pressure .ports communicate `with the companion working ports. Inthis way a positive move- 'It will be appreciated that the construction provides an arrangement in which the pressures on the various ports are always symmetrical about the axis so that there is no possibility of their producing a tendency to tilting of the moving parts under any conditions. In addition to this the layoutV is compact and .a relatively small size of yvalve can be employed Afor a given iiow.

What we claim as our invention and desire to `s ecureby Letters Patent is:

l. A duid control valve including a movable member mounted to rotate about an axis relatively to :a -platen member, the movable member and the platen kaffording cooperating end surfaces having in them cooperating ports in pairs, wherein each pair comprises two portsinone i of the members-centered on astraight line through :the

axis andonopposite sidesofrit, thetwo .ports of each 27 5 pairheinglnterconnectcdtsofthat the'uid'-fpressuresiinthe two ports of any one pair are the same, in which the movable member comprises a pair of telescoping sleeves arranged to turn together about the axis and interposed between the ported platen and a second platen spaced from it, while the two platens are mounted in an outer body and are held apart by a spacer engaging their opposed surfaces so as to hold them accurately parallel.

2. A uid control valve as claimed in claim 1 in which the spacer comprises a sleeve surrounding the movable member.

3. A iluid control valve as claimed in claim 2 in which the fluid pressure has a resultant tending to force the two platens together.

4. A iluid control valve including a movable member mounted to rotate about an axis relatively to a platen member, the movable member and the platen affording co-operating end surfaces having in them co-operating ports in pairs, wherein each pair comprises two ports in one of the members centred on a straight line through the axis and on opposite sides of it, the two ports of each pair being interconnected so that the uid pressures in the two ports of any one pair are the same, in which the movable member comprises a pair of telescoping sleeves arranged to turn together about the axis and interposed between the ported platen and a second platen spaced from it, while the two platens are mounted in an outer body and are held apart by a spacer engaging their opposed surfaces so as to hold them accurately parallel and in which the fluid pressure has a resultant tending to force the movable member and the ported platen together.

5. A uid control valve as claimed in claim 4 in which the spacer comprises a sleeve surrounding the movable member.

6. A fluid control valve as claimed in claim 5 in which the iluid pressure has a resultant tending to force the two platens together.

References Cited in the file of this patent UNITED STATES PATENTS 916,262 Brocke Mar. 23, 1909 

